My Friend's Mom: After her mother dies, Young-jae visits her older sister's house, who took care of herself like her, and reunites with her sister, Soon-ae. She is incredibly greedy and charming. With the provocation of Soon-ae, the two develop into a secret relationship. One day when she was having a hot night with her mature lead, her daughter got stuck between the two ... A young and sexy daughter, a seasoned and mature mother, and a man wandering between mother and daughter. An unprecedented triangular romance between the three begins.